The present invention relates to a paper handling apparatus of the type having a plurality of bins and a chuck unit and a stapler unit which are movable along the bins, and causing the stapler unit to bind an end portion of a stack of paper sheets which have been received from a copier or similar image forming apparatus, sorted, and then stacked on any one of the bins.
A copier, for example, is operable with an automatic document feeder (ADF) and a sorter which sorts a plurality of copy sheets associated with each of a plurality of documents in order of page and thereby produces a plurality of sets of copies. More specifically, while the ADF sequentially feeds the documents to a reading section of the copier in order of page, the sorter distributes the resulting copies of each document one by one to bins thereof. A paper handling apparatus capable of automatically stapling stacks of paper sheets each being distributed to respective one of bins in order of page is disclosed in Japanese Patent Laid-Open Publication (Kokai) No. 57-63561, for example. This kind of apparatus saves time and labor necessary for one to take out the stacks of copy sheets from the individual bins and staple them one by one. In the prior art apparatus, each paper stack is fully pulled out of the associated bin and transferred to an elevatable tray to be stapled there. Another paper stack to be stapled next is pulled out onto the stapled paper stack and stapled there. By such a sequence, a plurality of stapled sets of copies are piled up one upon another. While such a prior art paper handling apparatus allows the stapled copies to be readily taken out, it needs a bulky device for pulling out a paper stack onto the tray and a large exclusive space for the tray, resulting in an increase in cost and in space for installation.
In the light of the above, there has also been proposed a paper handling apparatus capable of automatically stapling paper stacks sorted into successive bins without increasing the overall size of the apparatus and the space for installation. This kind of apparatus has a plurality of bins arranged one above another, and a stapler and a chuck unit which are movable up and down along the bins. Paper sheets distributed from a copier or similar image forming apparatus into each bin are gripped together by the chuck unit and then pulled out to such an extent that a portion thereof to be stapled protrude from the bin. In this condition, the end of the paper sheets is stapled and then returned to the original position on the bin. This prior art apparatus, however, has some problems left unsolved, as enumerated below.
(1) Paper sheets coming in from a copier or a printer, for example, are distributed face down to each bin of the paper handling apparatus in order of page. The stapler, therefore, drives a staple into such a stack of paper sheets from the underside of the stack. More specifically, the stapler is moved from one bin to another while being held in an upside-down position. It follows that, when the stapler has run out of staples, one has to replace a staple cartridge from below the stapler by troublesome manipulations.
(2) The sorting section made up of the bins and sorting means and the binding section movable up and down along the bins for binding paper sheets distributed to the bins are constructed integrally with each other. This kind of construction invites an increase in production cost and is, therefore, intrusive for a user who needs only a simple binding function or does not need the binding function. The paper handing apparatus having such a complicated construction needs much time and labor for maintenance which will be performed at the time of production or failure. Hence, not only production efficiency and the quality are lowered, but also the products suffer from scattering.
(3) The housing of the paper handling apparatus has a stapler door which is openable for the replacement of a staple cartridge, maintenance of the stapler unit and chuck unit, etc. Besides, the housing has a sorter door and a sorter top cover for implementing the maintenance and inspection of paper transport paths and the removal of a jamming sheet. When any one of such doors and covers is opened, a door switch associated with the door is turned off to cut off the power supply immediately. If the door is opened while the stapler is in operation, a motor driving the stapler is immediately turned off to interrupt the stapling operation. This often causes a staple to stop the stapler or to be bent itself or locks the stapler with a paper stack bit into the stapler.